Terfenol-D Based Magnetic Field Sensor With Temperature Independence Incorporating Dual Fiber Bragg Gratings Structure

A magnetic field sensor with temperature insensitivity implemented by two fiber Bragg gratings (FBGs) structure is presented and experimentally demonstrated. In the proposed sensing probe, a Terfenol-D piece is bonded with the same type of two FBGs in different direction relative to magnetic field. Two center wavelengths of the notches of FBG filters are mainly determined by the magnetic field, and the two FBGs experience different magnetic-field-induced strain and the same thermal expansion, leading to the linear relationship between the wavelength drift difference and the magnetic field and temperature insensitivity. By monitoring the shift of the wavelength drift difference, the magnetic field measurement for thermal-insensitive interrogation of the magnetic field sensor can be realized. Owing to its compact and temperature independent advantages, the proposed sensor has potential application especially in the unstable direction of magnetic field. Moreover, the sensor can also serve the purpose of temperature measurement by monitoring one of the center wavelengths. The measured sensitivity of the magnetic field intensity of the proposed sensor is 8.77 pm/mT.